function [bz, az] = impinvar(b, a, Fs)
    [R, p, k] = residue(b, a);
    T = 1 / Fs;
    pz = exp(p * T);
    [bz, az] = residuez(T * R, pz, k);
    bz = real(bz);
    az = real(az);
end